Chapter 1013 Five Times Is Not Enough!

Chapter 1013 Five times... not enough!

Now that the technical principles and specific R&D routes have been clarified, the 54th Institute of China Electronics Technology has acted quite quickly.

This is also due to the fact that the other party has been working in the field of ground mobile communications for many years. As the two most important vehicle chassis communication equipment for the current project, they have actually entered the testing stage long ago.

It's just that the satellite communication vehicle has been limited in performance due to the relatively poor number and performance of China's own communication satellites.

After receiving Chang Haonan's project requirements, the 54th Institute took only about three weeks to complete the hardware transformation of the four prototype vehicles, making them equipped with complete receiving-decoding-storage-encoding-forwarding functions, becoming a true network coding data node.

Just for the convenience of testing, the decoding and encoding modules are designed to be completely turned off physically to minimize the performance impact of additional hardware on the control group.

As for the program for encrypting and decrypting information...

That's even less of a problem.

Chang Haonan had previously conducted tests in a wired network, and the program at that time only needed to be slightly modified.

In contrast, Zhejiang University was not slow, but they did not have any extra stratospheric airships.

It would take time to build new ones or bring down the ones that were already in the sky collecting meteorological data.

The progress was a little behind.

However, Chang Haonan was not prepared to change his plan because of this.

It didn't matter whether the principle verification was done in the sky or on the ground. .

Therefore, after the acceptance of the four modified relay communication vehicles, Chang Haonan sent them to the scheduled test area in the west of Meng Province.

As for why it was Meng Province...

Because Torch Group had a huge test field here.

Since Comrade Zhuang Bingchang had not yet successfully developed alfalfa and soybeans that met the requirements, and Chang Haonan himself had not yet found a polymer material that could provide sufficient shear resistance for the sand, this piece of land had not really started to play a role yet.

But after all, the right to use belonged to Torch Group, and there were no large towns within hundreds of kilometers around, so it was easy to get approval for radio transmission testing.

The only problem was that in 2002, there was no highway network that would later spread across the country, especially in relatively remote areas in the central and western regions.

So the four vehicles were first transported from Beijing to Qingcheng, the capital of Meng Province, by rail, and then they had to travel hundreds of kilometers by themselves, and it took nearly a week to get to the destination.

Of course, the whole process was escorted by special personnel from Torch Group and the 54th Institute of China Electronics Technology, and Chang Haonan did not need to follow in person -

The latter's work schedule did not allow him to waste so much time on the road.

As the general person in charge of the project, Chang Haonan flew to TMTZQ Bikeqi Airport the day before the test.

Then on the morning of the second day, he transferred to a Z-12 helicopter belonging to the Air Force Search and Rescue Brigade of the Beijing Military Region and arrived at a general aviation airport near the test site.

When the helicopter landed, Wu Wei and others who had arrived here in advance were naturally waiting near the apron.

General aviation airports mainly serve various types of helicopters, as well as small gadgets such as Yun-5.

The site conditions are naturally much worse than those of common civil aviation airports.

Even the runway and apron are only hardened non-paved ground.

And Chang Haonan did not have much experience in taking a helicopter before.

So, he jumped out of the cabin as soon as he confirmed that the helicopter had stopped.

Then he was blinded by the dust that had not yet completely fallen back to the ground...

Fortunately, the people who were waiting for him were far away and were rushing over, so they did not notice Chang Haonan's little embarrassment.

"Report to President Chang."

Wu Wei came to Chang Haonan:

"According to the previously determined process arrangement, the four prototypes have completed all inspections and are just waiting for you to officially issue the test order!"

Not far behind him, four SX2190 chassis communication vehicles were parked in groups of two, under two sheds made of camouflage cloth.

Looking at the dusty people in front of him, Chang Haonan took a deep breath, took two steps forward with a little emotion, and shook hands with Wu Wei:

"Thank you for your hard work."

Following the former's eyes, Wu Wei looked down at his clothes that were already stained with a layer of dirt:

"Oh... this is just the beginning..."

"We are on business trips for ten months a year, and we have seen all kinds of scenes... We are used to it."

He stretched out his hand to brush off the dust on his clothes.

But the effect was obviously not very good.

So he had to change the subject:

"Mr. Chang, the logistics comrades at the airport left lunch for you, you see..."

Chang Haonan didn't eat much in the morning, and it was already past noon, and he did feel a little hungry.

But looking at the four test vehicles in the distance that had even deployed their disc-shaped antennas, he still felt that time could not be wasted:

"Put the whole lunch box on me, and find an empty space to rest on during the test..."

"..."

The four communication relay vehicles, according to the test plan from easy to difficult, will start with a distance of 5 kilometers from each other, and gradually increase the distance in steps of 5 kilometers, until the farthest distance is 30 kilometers -

Affected by the height of the antenna and the curvature of the earth, the farthest distance for direct communication of this type of communication vehicle is 30 kilometers.

For further distance, scattering communication means will be used.

On the contrary, it is not conducive to the conduct of today's test.

As Chang Haonan officially ordered the test to start, cars 2, 3, and 4 left the parking lot in sequence and drove west along a dirt road.

As the signal transmission source, car 1 did not need to move. At this time, several technicians had begun to set up the antenna mast under the operation.

The communication test with an interval of 5 kilometers at the beginning did not need this thing.

But it was indispensable later.

A few minutes later, Chang Haonan also took Wu Wei into the compartment of car 1.

In fact, a conference room was specially vacated at the airport tower as the test command center.

However, in order to see the results as soon as possible, Chang Haonan chose to get on the car himself.

…

Although the road conditions on the unpaved road were very poor, a hundred kilometers was not a long distance for the vehicle after all.

About half an hour later, car 4, which was the farthest away, also reported that it had arrived at the scheduled location 15 kilometers away.

So.

The first round of testing officially began.

First, of course, it was the control group.

That is, according to the traditional relay mode, the relay station only receives and forwards data, but does not process the data.

"All cars are in place!"

The voice of Fu Mingyi, the on-site test commander, came from the radio:

"Car No. 1, start sending data!"

For a while, the originally noisy carriage was left with only the humming sound of the air conditioner and communication equipment, as well as the breathing of four people, including Chang Haonan.

The data content used for the test was set by Chang Haonan in advance, so the operator did not need to enter anything on site.

Just select the content on the operation interface and send it.

However, the program was compiled in less than a month, so there was no need to consider issues such as UI interaction.

Not to mention others, even Chang Haonan himself couldn't hold back when looking at the slightly simple interface.

Fortunately, the basic functions are relatively complete.

Not long after, the data transmission gradually came to an end.

There is no doubt that even without looking at the specific results, you can feel that the results are not optimistic-

Network throughput is not the "average network speed" in the general understanding, and the test method is not to transmit a certain amount of data files and then divide it by the final time, but to send a certain number of frames at a certain rate and calculate the frames transmitted by the device under test.

If the two are equal, then increase the sending rate and retest until the moment when the received frame is less than the sent frame, and the corresponding rate is the network throughput.

Therefore, it can be basically considered that the shorter the test time, the worse the result.

In addition, it is not difficult to see that although the result obtained by this test method is a bandwidth unit of one byte/second, it is not only related to the transmission bandwidth.

What is more important is stability.

"1.4 kilobytes/second..."

Wu Wei subconsciously read it out almost the moment the number appeared on the screen.

Even in the early 21st century, it was a result that was so slow that it was shocking.

As he had estimated before, on the ground with poor transmission conditions, using communication vehicles for multi-hop transmission would not have any good results.

In fact, the throughput measured by the second vehicle was as high as 170 kilobytes/second.

By car No. 3, there were still about 30 kilobytes/second left...

And car No. 4 only had 1.4 kilobytes/second left.

It is enough to see the devastating impact of adding relay nodes on transmission speed.

Of course, such an exaggerated result is indeed a special case caused by large local natural interference.

But the trend is always correct.

"Turn on the encoding and decoding functions of each car and retest!"

Chang Haonan recorded the experimental data and then ordered on the radio.

For him, the worse the results of the control group, the closer to success.

However, the premise of everything is.

The experimental group can really measure a better data.

...

As the cooling fan of the cabinet hums again, the second test officially begins.

Theoretically, after the encoding and decoding functions are turned on, the network throughput will be close to the Shannon limit.

Although there will still be many impacts in actual operation, in any case, the results should be clearly better than before.

And the test process did not disappoint everyone.

The duration was several times longer than the first time.

Although the result is only positively correlated with the length of time, rather than proportional, it is at least a good sign.

It was not until more than ten minutes later that a number representing the throughput of vehicle No. 4 popped up on the screen as before.

"6.8 kilobytes/second!"

This result made Wu Wei's eyes light up.

You know, these numbers themselves do not represent the true level of his communication vehicle.

But the improvement is real.

Nearly 5 times!

He has no doubt that if his own products use this technology, then even after 5 years or even 10 years, the performance will not be completely outdated...

"Mr. Chang, this..."

He looked at Chang Haonan excitedly, ready to express his congratulations.

But when he said it, he found that the other party's face... didn't look very good.

"That's not right..."

Chang Haonan frowned slightly, staring at the result on the screen and muttered.

The slightly weird reaction directly confused Wu Wei:

"No... what's wrong?"

"..."

What greeted him was silence.

After a while, Chang Haonan said softly, whether he was talking to himself or answering a question:

"I tested it in a wired network before, and the result was never lower than 15 times... How come the effect was directly weakened by two-thirds this time?"

Hearing this, Wu Wei almost choked on his own saliva -

Oh my god, does this mean that the five-fold improvement is not big enough?